Automatic safety-joint for electric conductors



@No Model.)

J. H. GERRY. l AUTOMATIG- SAFETY JOINT POR ELECTRIC GONDUGTORS.

N0. 505,032. Patented Sept. 12, 1893.

W/T/VESSES.' l /NVENTHf l fw UNITED STATES PATENT OFFICE.

JAMES H. CURRY, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR OF EIGHTY- THREE ONE-HUNDRED-AND-TWENTY-EIGHTHS TO FRANK B TOMB, OF SAME PLACE, AND SAMUEL J. GRAHAM, A. H. CHILDS, AND ROBERT A. GILLESPIE, OF PITTSBURG, PENNSYLVANIA.

AUTIVIATIC SAFETY-JOINT FOR ELECTRIC CONDUCTORS.

SPECIFICATION forming part of Letters Patent No. 505,032, dated September 12, 1893. Application iiled November 18,1892. Serial No. 452,394. (No model.)

To all whom it' may concern.-

' Beit known that I, JAMES H. CURRY, residing at Wilkinsburg, Allegheny county, in the State of Pennsylvania, have invented a new and Improved Automatic Safety-Joint for Electric Conductors, of which the following is a specification.

The object of my invention is to provide an improved automatic safety joint for elec- Io trical conductors.

In the Patent No. 431,516 in connection with another inventor, I provided, a coupling, in which the wire conductors were formed with buttons or heads within a hollow metal casing,

between which heads and the ends of the casing springs were arranged which, when tension was put on the wire by Stringing the same on poles, caused the said heads or buttons to compress the springs and bear against and zo form electrical connection with the casing,

and when tension on the conductor was relieved, by the accidental breaking of the wire, would allow the springs to throw the buttons or heads out of bearing against the ends of 2 5 the casing and break connection in the wires for some distance on each side of the point of severance, so that these terminals are no longer live wires andinvolve no danger to persons accidentally touching the same, or to the 3o line men in handling them for repairs. .In the electrical contact formed in this case by tension on the wire, the separation of the contact faces is effected not only by the severance of the wire, but by very slight relaxa tions of tension in the wire, such as expansion from heat, the leaning of a pole, and such other causes as ought not to interfere with the continuity and normal operation of the circuit. Furthermore as the electric circuit 4o was made through the casing the latter was a live surface. My present invention comprises a special constructionin which the outer casing is always insulated from the line currents and is never a live surface, thus reducing danger to the line men, and in which contact is made or broken between two terminals concentrically arranged within the casing in a manner to provide for slight variations in tension of the wire, and in which construc- `they assume when tension is entirely relieved by the severance ofthe wire, and the current through the joint is broken, and Fig. 4 is a View in perspective of the two adjacent parts of the sliding contact. V

i In the drawings A represents the outer casing of the joint which may be made either of metal or other suitable material as there is no `current which passes through the casing as a conductor. The casing is made of two coni- 7o cal sections united in the middle by a screw joint, each section being, when made of metal, lined inside with an insulating or non-conducting bushing.

Through the two sections of the casing there pass the two conductor stems B O which have outside the casing perforations into which are inserted the ends of the line wire and secured by twisting in the usual manner. The stem B terminates inside the casing in a hollow cy- 8o lindrical metal sleeve h, which is preferably made detachable from the stem B and screwed onto the same as shown. This sleeve has an inwardly projecting flange h at its outer edge, and inside of this ange the sleeve hasa nonconducting lining b2 of insulating material, while four longitudinal slots divide this sleeve into as many spring tongues. The stem C terminates in a metal boss or hub c which is preferably made of a separate piece and screwed 9o on as shown. Just behind the hub and retained between it and a flange c on the stem is a grooved collar`c2 of insulating material whose groove is of less diameter than the hub c, and whose groove is also wide enough to receive the liange h of the sleeve on the other stem. Behind the flange c of stem C there is disposed about the stem a spiral spring D which bears at its outer end against the insulating bushing of the case and. tends to throw the stem C inwardly. Behind the sleeve b of the stem Bis another spiral spring D which tends also to throw that stem inwardly. Now when the joint is in place in a circuit Wire, and the proper normal tension is on the two stems B and C, the inturned flange b of sleeve b rests upon the hub c of the other Stem with a pressure determined by the elasticity of the spring tongues and electrical contact is made from one stem to the other. If any variation iu tension on the line wire occurs from causes which should not break the circuit, the hub and sleeve simply slip with the sliding contact the one into or out from the other, still preserving, however, the electrical contact, and this compensating sliding contact may be as great or as little as may be desired, usually from one to three inches. If, however, an actual break or severance of the wire occurs, then the spiral springs throw the two stemsinwardly to their full extent, and the hub slipping into the sleeve allows the inturned flange b of the sleeve to drop into the grooved collar c2 of insulating material, thus breaking the circuit and locking the parts of the safety joint in this position. I

In carrying out my invention it will be seen that only one contact is used and when this is broken it is broken by their contact surfaces passing by or past each other, in contradistinction to using two contacts that simply separate. Furthermore no current is ever transmitted through the case, and as the case is not alive surface, it need not be covered by any webbing or electrical jacket of insulating material.

In my invention as described, I have only shown one form of the sliding contact, t'. e., th e slotted cylindrical sleeve and internal hub, but it is obvious that any form of spring tongues with opposite contact surfaces might be employed without departing from my invention.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

l. An automatic safety joint for electric conductors consisting of an insulated containing case, conducting stems passing through the ends of the same, springs for forcing these stems inwardly, and two sliding electrical contact surfaces arranged upon the inner ends of these stems and adapted to break circuit by being moved inwardly past each other, and

insulation disposed between the conducting stems and contacts ou the one hand, and the containing case on the other, to maintain a permanent insulation for the containing case in yall positions of the parts, substantially as described, and shown.

2. An automaticsafetyjoint forelectric conductors, consisting of an insulated containing case, conducting stems passing through the ends of the same, springs for forcing these stems inwardly, two sliding electrical contact surfaces arranged upon theinner ends of these stems, and a non-conducting locking seat of insulating material arranged upon one of the stems behind its contact surface, for the other contact surface to drop into, substantially as shown and described.

3. The conductingstem B,with slotted inetal shell having an inturned fiange at the end and insulation within; in combination With the conducting stem C having a metal hub with a non-conducting grooved collar behind it, springs for forcing the stems inwardly, and an outer insulated containing case, substantially as shown and described.

JAMES H. CURRY Witnesses:

A. C. MUNHALL, EDWIN LOGAN. 

